Bearing assemblies are present whenever rotary motion of a machine part is required. Bearing assemblies are often available as mounted bearings which are bearings that are installed in preconfigured housings. Such an arrangement simplifies machine design as the problems of bearing contamination and maintaining the bearing in contact with a shaft are solved for the machine designer who can select and purchase an off-the-shelf mounted bearing package with a housing that has mounting holes, seals, a bearing and a locking system to hold the bearing to the shaft.
Examples of prior bearing assemblies and locking systems known to the inventors include those disclosed in the following:                U.S. Pat. No. 1,116,845 to Rogers        U.S. Pat. No. 1,380,708 to Ford        U.S. Pat. No. 1,759,640 to Brunner et al.        U.S. Pat. No. 2,764,437 to Bratt;        U.S. Pat. No. 3,709,575 to Howe, Jr.        U.S. Pat. No. 3,806,215 to Price et al.        U.S. Pat. No. 3,816,013 to Schuhmann        U.S. Pat. No. 3,912,412 to Struttmann        U.S. Pat. No. 3,918,779 to Halliger et al.        U.S. Pat. No. 4,596,477 to Lundgren        U.S. Pat. No. 4,916,750 to Scott        U.S. Pat. No. 5,011,306 to Martinie        U.S. Pat. No. 5,489,156 to Martinie        U.S. Pat. No. 5,582,482 to Thom, Jr, et al.        U.S. Pat. No. 5,685,650 to Martinie et al.        U.S. Pat. No. 5,876,127 to Casey        U.S. Pat. No. 5,987,214 to Nisley        U.S. Pat. No. 6,152,604 to Ostling et al.        U.S. Pat. No. 6,425,690 to DeWatcher, and        U.S. Published application No. 2002/009418 to Ostling et al.        
Bearing assemblies that incorporate spherical roller bearings are a preferred form of assembly. Spherical roller bearing assemblies employ cylindrical rollers turning between two races to permit relative rotation of parts associated with each race. The advantage of spherical roller bearings is that they can accommodate both radial and axial loads at high loading levels and also accept some misalignment. These features make mounted spherical roller bearings, the preferred choice for any machine that must handle heavy loads at low or intermediate speeds. Mounted spherical roller bearings are found in all heavy industry from forestry to steel manufacturing to automotive assembly lines and food processing. They are used in power plants, scrap yards, mines sand and gravel operations and almost any industry.
One of the biggest problems in designing a mounted bearing is coming up with a locking system to hold the bearing tight to the shaft. A spherical roller bearing will accept thrust loads in both axial and radial directions, but this is of no benefit if the bearings slide on the shaft when an axial load is applied. One solution to this problem is to include an eccentric locking collar to hold the bearing housing to the shaft. The drawback of the eccentric locking collar becomes apparent when it is necessary to remove the bearing. Generally, bearings located by eccentric locking collars can only be removed with a cutting torch if they have been in service for any reasonable period. This is a significant problem if the bearings are mounted to expensive machinery that requires dismantling for maintenance or repairs. Removal by cutting torch also tends to damage the bearing such that an otherwise serviceable bearing must be replaced during each maintenance operation.
Tapered adapter mounted bearings are a different solution to the problem of locking a bearing housing to a shaft. These bearings use a tapered adapter comprising a tapered sleeve that is pulled or pushed into a bearing housing with a tapered bore. The tapered sleeve and bore create an interference wedge fit that locks the bearing housing to the shaft. The further the sleeve is inserted into the bore, the tighter the interference fit becomes. Tapered adapter mounted bearings are fairly easily removed from the shaft by pushing the bearing in reverse against the taper.
There are also drawbacks to current tapered adapter mounted bearings including:                1) the insertion of the tapered sleeve into the tapered bore of the bearing housing reduces the running clearance of the bearing. It is difficult to know how far to insert the tapered sleeve to lock the bearing housing on the shaft without adversely affecting the performance of the bearing by reducing clearance such that the bearing overheats during normal operation. Currently, the best method to alleviate this problem is to use feeler gauges between the rollers and the races when installing the bearing on the shaft to monitor clearance.        2) the tapered adapter serves to hold the shaft well in applications with high radial loads, however, performance with respect to axial loads is less impressive. The tapered adapter will only accept limited axial loads before slippage along the shaft may occur.        3) the tightening of the tapered adapter will axially preload the bearing if the bearing housing is held firmly in place.        